Ship propeller having rotatable blades



Sept. 16, 1941. .1. E. ENGLESSON 2,255,920

' SHIP PROPELLER HAVING ROTATABLE BLADES Filed Jan. 12, 1938 J van/or.-

Patented 16, 1941 smr raorELLEn. HAVING BOTATABLE numes John ElevEnglesson, Kristineliamn, Sweden Application January 12, 1938, SerialNo. 184,513

In Sweden February 1 Claim.

protected from water which might cause corrosion of the same with aresultant rapid decrease of the endurance strength of the springs. v

With this purpose in view the springs are placed, according to thepresent invention, in the pressure chamber of the servomotor which isfilled with oil or a fluid which does not cause corrosion, and in whicha pressure is ordinarily maintained which is considerably higher thanthe pressure of the water outside the propeller hub. When located in thesaid chamber the spring or springs '15 or are eflfectively protectedagainst the corrosive-action of ,water which would lower the strengthof.the same. Even it the flange or the packing ofia blade h p ns to becomedamaged, so that water penetrates into the cavity in the hub in whichthe crank pins of the #blades are located, such water cannot reach thesprings due to the high pressure in the pressure chamber of theservomotor.

The accompanying drawing shows by way of example a constructional formof the invention. The drawing shows an axial section through the hub ofa ship propeller in which the rotatable blades are adapted to be set bymeans of a hydraulic servomotor.

In-the propeller hub illustrated, l denotes the hub body which isrigidly connected to the hollow propeller shaft 2. In bushings 3 and lin 'said two members the hollow piston rod 5 is movable in the axialdirection, the servomotor piston 6 being secured to the left-hand .endof said rod: Said piston is movable in the servomotor cylinder 1 whichis closed by the head 8, the outer portion of which is formed as a hubcone 8a, and which is secured to the cylinder 1 by means of screws 9.III denotes one of the propeller blades which by means of its flange andthe crank pin ring H is journalled on a ring l2 secured to the hub bodyI, in such manner that the blade is rotatable on an axis perpendicularto the axis of the hub body.

Made integral with the crank pin ring H is a crank pin I which turns ina slide block l3 which is slidable in a groove in a projection from thepiston rod 5, said groove being perpendicular to the axis of the pistonrod 5. Secured in the sleeve II which forms a seat for a hollow controlslide l8 which is movable in the axial direction. Said slide I6 isconnected to the slide rod 11 which extends through the hollow propellershaft 2, and which is also hollow so'that pressure liquid, such as oil,may be supplied through the same for actuating the servomotor.

, In a manner previously described in my U. S. Patent No. 1,510,436 ofSept. 30, 1924, the slide it and the sleeve I! as well as the portion ofth piston rod surrounding the latter are so shaped and provided withpassages so arranged that when the slide I6 is moved a distance in onedirection or the other, pressure liquid is supplied to the chamber onthe right-hand or left-hand side of the servomotor piston 6 in suchmanner that the piston is caused to move in the same direction as theslide l6. For this purpose the slide I6 is provided with two peripheralrecesses 3| and 32 which communicate through holes 33 and 34,respectively, with the bore in the slide l6. Upon movement of the slideit to the left from the position shown in the drawing, the recess 3| isput in communication with a port 35 leading through the walls oi thesleeve l5 and piston rod 5 to the chamber on the right-hand side of thepiston 5, so that pressure liquid is supplied to said chamber, and thepiston is also moved to the left. Again, upon movement of the slide Itto the right from the position shown in the drawing, the recess 32 isput in communication with a port 36 leading through the walls of thesleeve I 5 and piston rod 5 to the chamber on the left-hand side of thepiston 6, which will thus move-to the right. Upon movement of theservomotor piston 6 the blades 1 II are turned through the medium of theparts 5, l3, I4, and II. The space l8 between the piston rod 5 and theslide it serves, in a manner previously known, as a discharge conduitfor pressure liquid from the servomotor.

According to the invention there are inserted in the cylinder head 8, i.e. in the pressure chamber of the servomotor on the left-hand side ofthe piston 8, two strong helical compression springs I! and 2B, theright-hand ends of which bear against the servomotor piston 6, while thelefthand ends of the same bear against a disk 2| which in its turn bearsagainst a shoulder in the left-hand end of the hollow piston rod 5 is ahead 8. If, for any reason, the supply of pressure liquid ceases so thatthe pressure on the right-hand side of the piston 6 ceases, the piston 6is moved by the springs I9, 20 to the right in the drawing, until itcomes to bear against the bottom of the servomotor cylinderl. In thisway the propeller blades II are turned to the position for going ahead.

Itwill be understood that for this purpose the springs must be sopowerful that they are capable of iovercoming the frictional forces inall links and bearings and of moving the blades to and retain them inthe said position. The provision of. the springs II, 2I thus guardsagainst the ship becoming incapable of maneuvering, if the pumpsupplying pressure liquid to the servomotor fails, and the blades IIhappen to occupy inoperative position.

as shown in the drawing, the outer diameter of the helical spring 2I isonly slightly less than the inner diameter of the pressure chamber, 1.e. oflthe portion of the head I that surrounds said spring, with a viewto prevent too large oscillations of the spring in the transversedirection.

In order that the diflerence in spring tension not be too large when theservomotor piston occupies its left-hand and right-hand extremepositions, it is necessary to use comparatively long springs i 9, 2I. Inorder to facilitate mounting and dismounting of these long powerfulsprings the following arrangement is provided. Screwed onto theleft-hand end of the piston rod 5 is a stop nut 22 which is intended tocooperate with a stop flange 22 of the disk 2|. These parts are arrangedin such relation to one another that the flange of the stop nut 22 bearsagainst the flange 22 when the servomotor piston I bears against thebottom of the cylinder I.

Now, if the screws I which hold the head I to the cylinder 1, areunscrewed, the spring tension is jtaken up by the portion of the pistonrod I between the piston I and the stop nut 22. The

head I can then be directly taken off, after which ayoke is forcedagainst the disk 2| by means of longer screws inserted into some of theholes for the screws I. The stop nut 22 is' now unscrewed,

and the springs are relieved of tension. The mounting of the springs ismade in a similar manner but in the reverse order.

1 The constructional form above described and illustrated in the drawingis only to be regarded as an example and it will be'understood that itis capable of modification in various ways in respect of its detailswithout departing from the principle of the invention.

I claim: In an adjustable propeller blade assembly, a hollow shaft, ahub surrounding the end thereof and having a removable end cap, bladesrotatably mounted in said hub, a sleeve having a piston secured thereonand slidable on said shaft, connections between said sleeve and saidblades to rotate the latter, said piston being mounted to reciprocate ina cylindrical'chamber in said hub, said chamber having a removable endwall seated in said cap, a helical spring positioned in said cylindricalchamber with a slight clearance between the two and confined betweensaid piston and said removable end wall to thereby tend to maintain saidpiston and blades normally in one of two extreme positions for normaloperation of the propeller, and valve means admitting a noncorrosivefluid under pressure from said hollow shaft to said cylindrical chamberto move said piston one way or the other, said spring being continuallyimmersed in said non-corrosive fluid to prolong the life thereof.

JOHN ELOV ENGLESSON.

